The present invention relates to a process for the manufacture of carbon oxysulfide from methanol.
Carbon oxysulfide, also known as carbonyl sulfide, is a well known compound which has heretofore been used as an active reagent in various processes. For example, carbonyl sulfide is more reactive than carbon dioxide and has been suggested as a suitable reagent to react with ammonia in the synthesis of urea. Similarly, carbonyl sulfide is an excellent source of useable atomic sulfur and it has been used in the synthesis of sulfides from olefins, such as episulfides, alkenylthiols and vinylic thiols. Carbonyl sulfide also reacts with alcohols in the present of alkalis to form monothiocarbonates.
It is known that carbon oxysulfide is obtained whenever a mixture of carbon, oxygen and sulfur, or a mixture of compounds containing these elements, such as carbon monoxide, carbon disulfide and sulfur dioxide is heated to an elevated temperature. However, the preferred conventional methods of manufacturing this product essentially involve either the sulfurization of carbon monoxide by sulfur dioxide at a high temperature in the presence of carbon, or by sulfur in the presence of a catalyst, or the sulfurization of a mixture of hydrocarbons, air or CO.sub.2 by sulfur, under elevated pressure and in the presence of a catalyst.
However, the recent difficulties in obtaining a continuous and adequate supply of hydrocarbons and the current energy crisis have forced industry to utilize certain starting materials which have hitherto been little used in the manufacture of chemical intermediates. As a consequence of present energy and economic conditions, the aforementioned conventional methods of producing carbon oxysulfide no longer constitute acceptable synthesis reactions.
Accordingly, the present invention is directed to a process for preparing carbon oxysulfide that does not require the use of relatively expensive hydrocarbon reactants which are in short supply or necessitate the utilization of carbon monoxide which due to its toxicity constantly presents a serious problem with respect to safety and processability.